gosl: read-or-write var flag working for Context like variables that …

…are mostly read-only but sometimes writeable.

gosl/examples/basic/shaders/Compute.wgsl

@@ -57,7 +57,7 @@ fn ParamStruct_IntegFromRaw(ps: ParamStruct, idx: i32) {
 	SubStruct_IntegFromRaw(ps.Sub, idx);
 }
 fn Compute(i: u32) { //gosl:kernel
-	let Params=Params[0]; ParamStruct_IntegFromRaw(Params, i32(i));
+	let params=Params[0]; ParamStruct_IntegFromRaw(params, i32(i));
 }
 
 //////// import: "atomic.go"

gosl/gotosl/gengpu.go

@@ -197,7 +197,7 @@ func (st *State) GenGPUSystemInit(sy *System) string {
 			} else {
 				b.WriteString(fmt.Sprintf("\t\t\tvr = sgp.AddStruct(%q, int(unsafe.Sizeof(%s{})), 1, gpu.ComputeShader)\n", vr.Name, vr.SLType()))
 			}
-			if vr.ReadOnly {
+			if vr.ReadOnly && !vr.ReadOrWrite {
 				b.WriteString("\t\t\tvr.ReadOnly = true\n")
 			}
 		}

gosl/gotosl/genkernel.go

@@ -36,8 +36,7 @@ func (st *State) GenKernelHeader(sy *System, kn *Kernel, avars map[string]*Var)
 		}
 		for vi, vr := range gp.Vars {
 			access := ", read_write"
-			rw := st.VarIsReadWrite(vr.Name)
-			if vr.ReadOnly && !rw {
+			if vr.ReadOnly && !vr.ReadOrWrite {
 				access = ", read"
 			}
 			if gp.Uniform {

gosl/gotosl/gotosl.go

@@ -52,7 +52,7 @@ type Kernel struct {
 	// Lines is full shader code
 	Lines [][]byte
 
-	// ReadWriteVars are variables marked as read_write for current kernel.
+	// ReadWriteVars are variables marked as read-write for current kernel.
 	ReadWriteVars map[string]bool
 }
 
@@ -71,6 +71,12 @@ type Var struct {
 	// It is important to optimize GPU memory usage to indicate this.
 	ReadOnly bool
 
+	// ReadOrWrite indicates that this variable defaults to ReadOnly
+	// but is also flagged as read-write in some cases. It is registered
+	// as read_write in the gpu ComputeSystem, but processed as ReadOnly
+	// by default except for kernels that declare it as read-write.
+	ReadOrWrite bool
+
 	// True if a tensor type
 	Tensor bool
 

gosl/gotosl/nodes.go

@@ -2690,8 +2690,12 @@ func (p *printer) systemVars(d *ast.GenDecl, sysname string) {
 		vs := s.(*ast.ValueSpec)
 		dirs, docs := p.findDirective(vs.Doc)
 		readOnly := false
+		readOrWrite := false
 		if hasDirective(dirs, "read-only") {
 			readOnly = true
+		} else if hasDirective(dirs, "read-or-write") {
+			readOnly = true
+			readOrWrite = true
 		}
 		if gpnm, ok := directiveAfter(dirs, "group"); ok {
 			if gpnm == "" {
@@ -2754,7 +2758,7 @@ func (p *printer) systemVars(d *ast.GenDecl, sysname string) {
 			}
 			typ = sid.Name + "." + sel.Sel.Name
 		}
-		vr := &Var{Name: nm, Type: typ, ReadOnly: readOnly}
+		vr := &Var{Name: nm, Type: typ, ReadOnly: readOnly, ReadOrWrite: readOrWrite}
 		if strings.HasPrefix(typ, "tensor.") {
 			vr.Tensor = true
 			dstr, ok := directiveAfter(dirs, "dims")

gosl/gotosl/testdata/Compute.golden

@@ -7,7 +7,7 @@ var<storage, read> TensorStrides: array<u32>;
 @group(0) @binding(1)
 var<storage, read> Params: array<ParamStruct>;
 @group(0) @binding(2)
-var<storage, read> Ctx: array<Context>;
+var<storage, read_write> Ctx: array<Context>;
 // // Data is the data on which the computation operates. // 2D: outer index is data, inner index is: Raw, Integ, Exp vars. // 
 @group(1) @binding(0)
 var<storage, read_write> Data: array<f32>;

gosl/gotosl/testdata/basic.goal

@@ -16,8 +16,9 @@ var (
 	//gosl:read-only
 	Params []ParamStruct
 
-	// Ctx provides additional context.
-	//gosl:read-only
+	// Ctx provides additional context, and is usually read-only,
+	// but is updated in a specific kernel flagged as read-write.
+	//gosl:read-or-write
 	Ctx []Context
 
 	// Data is the data on which the computation operates.

gosl/gotosl/testdata/gosl.golden

@@ -58,7 +58,6 @@ func GPUInit() {
 			vr = sgp.AddStruct("Params", int(unsafe.Sizeof(ParamStruct{})), 1, gpu.ComputeShader)
 			vr.ReadOnly = true
 			vr = sgp.AddStruct("Ctx", int(unsafe.Sizeof(Context{})), 1, gpu.ComputeShader)
-			vr.ReadOnly = true
 			sgp.SetNValues(1)
 		}
 		{